The present invention relates to U.S. Pat. No. Re 28,168 entitled "SOLID-STATE POWER SUPPLY SYSTEM FOR ROTATING ANODE X-RAY TUBES," and to U.S. patent application, Ser. No. 516,752, entitled "VARIABLE SPEED STARTERS FOR X-RAY TUBES," both in the name of Louis L. Fiocca and both assigned to the same assignee as the present invention. For purposes of simplification of the description of the circuitry in this application, reference as appropriate is herein made to said U.S. Pat. No. Re 28,168 and to said patent application, Ser. No. 516,752, now U.S. Pat. No. 3,968,413.
The control system of the present invention provides a means of controlling the starter and drive system for the anode of the associated X-Ray tubes. The rotors of the associated tubes are selectively controlled to accelerate or boost the rotor to a relatively low running speed, and to a second relatively high running speed, and either of the selected running speeds can be varied within a given operating range. Further, a selected braking sequence is provided to decelerate or brake the rotating anode dependent on the running speed.
An X-Ray examination room will conventionally have at least two X-ray tubes; one of the tubes is normally used for doing fluoroscopic examinations and the other tube is normally used for doing radiographic exposures. For doing such fluoroscopic examinations, the undertable tube is operated at a relatively low speed. In contrast, radiographic exposures are preferably done at high speeds, say at 10,800 RPM, and therefore the rotating speed of the overtable tube must be boosted to a high running speed. The present invention provides a control system for a starter and drive means for accelerating and operating the rotating anodes of one or more tubes of an X-Ray examination room at the required operating speeds.
A portion of the circuitry of the present invention is the same as that described in the U.S. Pat. No. Re 28,168, and reference is specifically made to that patent as needed to amplify the description of the present invention.
The rotor controller system of the invention provides fast acceleration of the X-Ray tube anodes for a selected one of three separate tubes which tubes may be of differing voltage and current ratings. It is desired that these tubes be accelerated to the running speed in a minimum of time.
The system provides a direct current dynamic braking circuit which controllably decelerates the X-Ray tube anode from its running speed to less than a few hundred RPM's. The foregoing increases bearing life and minimizes tube breakage by causing the rotor to pass quickly through its resonant frequency vibration modes as it is decelerated.
The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of the preferred embodiments of the invention, as illustrated in the accompanying drawings wherein: